Automatic pressure controlled gate valve



y 1939- M. A. THOMASON 2,160,766

AUTOMATIC PRESSURE CONTROLLED GATE VALVE Filed April 22, 1937 2 Sheets-Sheet l M06704 Tka ma'azv flwzyzmrl ATTORNEY y 30, 1939- M. A. THOMASON 2,160,766

AUTOMATIC PRESSURE CONTROLLED GATE VALVE Filed April 22, 1937 2 Sheets-Sheet 2 ATTORNEY WITNESS 50 on the pistons I3 andl4.

Patented May 30, 1939 PATENT OFFICE AUTOMATIC PRESSURE CONTROLLED GATE VALVE Mavin A. Thomason, Lake Charles, La. Application April 22, 1937, Serial No. 138,398 1 Claim. 7 (01. 137-153) This invention relates to automatic pressure controlled gate valves to be employed in fluid pressure pipelines and has for the' primary objectthe "provision of a device of'this character which will in case of a break in the pipeline automatically close said pipeline between the break and the fluid pressure source to prevent loss of the fluid from said source and which may be easily and quickly restored to normalcy when m the break has been repaired.

With these and other objects in view, this invention consists in certain novel features of construction, combination and arrangement of parts to be hereinafter more fully described and is claimed.

For a complete understanding of my invention, reference is to be had to the following description and accompanying drawings, in which Figure -1 is a vertical sectional' view illustrat- O ing an automatic pressure "controlled gate valve connected in a pipeline and constructed in accordance with my invention.

Figure 2 is a fragmentary vertical sectional view showing pipelines closed by my invention 25 when a break occurs in said pipeline.

Figure 3 is a fragmentary side elevation il1us-, trating a modification of my invention.

Referring in detail to the drawings, the numeral I indicates a pipeline in which fluid flows 30 in the direction indicated by the arrow from a source (not shown). This fluid is under pressure. Connected in the pipeline I is a gate type valve 2, consisting of a casing 3 having a valve seat 4 and a slidable valve element 5 connected 35 to a valve stem 6. Located adjacent the gate valve is a main pressure cylinder 1 having slidable therein a piston 8, the stem 9 thereof being connected to the stem 6 of the gate valve. A

spring I acts on the piston 8 to move said piston in a direction for opening the gate valve, thereby rendering the gate valve of a self-opening type which permits the fluid to flow freely through the pipeline I.

Arranged adjacent the cylinder 1 are cylinders 45 II and [2 both of the same construction and have slidable therein pistons I3 and I4. Pipes I and I6 connect corresponding ends of the cylinders II and I2 to the pipeline I at opposite sides of the gate valve. Springs I1 and I8 act These springs may be readily adjusted for increasing and decreasing their actions upon the pistons. The adjustment to the springs can be made in any well known manner. The cylinders II and I2 at one side of the pistons thereof are each provided with ports I9 and arranged in close relation to each other. The stems of the pistons I3 and I4 have secured thereto slide valves 2| which during the different positions of said pistons I3 and I4 open and close the ports 20. Reservoirs 22 and 23 are connected to the pipeline I by pipes 24 and 25 in which are located check valves 26. The check valves open to admit fluid pressure from the pipeline I to said reservoirs and close when the fluid pressure in the pipeline 1;) falls below the pressure in the reservoirs. The pipes 24 and 25 connect to the pipeline I at opposite sides of the gate valve. The reservoirs 22 and 23 connect to the ports IQ of the cylinders II and I2 by pipes 21. The ports 29 of the 1. cylinders II. and I2 are connected by a pipe 28 which is in turn connected to a branch pipe 29 and the latter is connected to one end of the main pressure cylinder I. A control valve 30 is located in the branch pipe 29, The end 20 of the cylinder I which has the branch pipe 29 connected thereto is provided with a bleed valve 3i.

The cylinders II and I2 each are composed of sections detachably connected and clamped between said sections is a combined gasket and seat 32. The combined gasket and seat besides establishing leak proof connections between the sections of said cylinders II and I2 are engaged by the pistons I3 during the operation of this device to prevent leakage and which will be hereinafter more fully described.

Instead of having the reservoirs 22 and 23, as shown in Figure 1, they may be joined to' gether, as shown in Figure 3, and provide a support for the cylinders II and I2. Also the reservoirs, as shown in Figure 3, when joined together are preferably located in close proximity to the cylinder 1 thus rendering this device more compact. 40

During normal operation of this device, that is, when the fluid is flowing through the pipeline I in the direction of the arrow in Figure 1 from a source (not shown) and with the pipeline free of a leak, the fluid pressure of the 5 pipeline enters the cylinders I I and I2 upon each side of the pistons I3 and I4 by way of the pipes 24, 25, and 2! and the pipes I6 and I5. The fluid pressure on each side of the pistons I3 and I4 is equal, however, the springs I1 and I8 acting on said pistons position them as shown in Figure 1 so that the valves 2I close the ports 20 and thereby prevent the fluid pressure of the pipeline from reaching the cylinder 1 and acting on the piston 8. The piston 8 being spring sure falls therein which pressure eflects the pressure in the pipes 24, 25, I6 and IS. The .check valves 26 immediately close trapping the pressure in the reservoirs 22 and 23. The pressure lowering in the pipes l and I6 brings about unequalization of pressure on each side of :the pistons l3 and I4. Owing to the trapped pressure in the reservoirs 22 and 23 thereof this pres sure cver'co'rnesthe action of the springs "I1 and permitting the pistons l3 and 44 to slide moving therewith the valves 2| to open the ports 20. The press'ure of the reservoirs 22 and 23 then passes into the cylinder 1 by way of the pipe .28 and branch pipe 29 acting on the piston '8, driving said piston against the action of the spring i0 to seat the valve element 5 of the gate valve thereby closing the pipeline to the leak. The pipeline being now closed to the leak, the pressure therein builds up between the source and the gate valve. This pressure enters the pipes 24 and [-6 causing the piston l3 in the cylinder H to move to the right in Figure 1 or to assume the-position as shown in Figure 2, and the piston 14 of the cylinder l2 to move to the left in Figure 1 or to assume the position, as shown in Figure 2. The pistons 13 and I4 thus positioned bring about opening of .the port 20 in the-cylinder H and closing the port 20 in the cylinder 12. The fluid pressure then enters the pipe 28 from the cylinder H and acts directly against the piston 8 to retain the gate valve closed. The piston I3 when moving to the position shown in Figure 2, .contacts the combined gasket and seat .32 of the cylinder II to prevent leakage while the piston M of the cylinder 12 is forced tightly against the shoulder in the cylinder to prevent leakage. When the leak has been repaired and it is desired to restore the flow through the pipeline, the bleed valve 3| is opened and the valve 3|] is closed. The pressure is then cut off from the cylinder 1 to the pipeline and the spring l0 returns the piston 8 to its normal position opening the gate valve. As the flow is restored through the pipeline by opening'of the gate valve the bleed valve 3| is closed and the valve 30 opened. The pressure in the pipeline then acts to restore the pistons l3 and "Mata their initial position, or as shown in Figure :1.

The invention is then ready to automatically close the pipeline when a second leak de- Having described the invention, I claim: In combination with a pipeline for conveying fluid under pressure from a source, a valve connected ,in said pipeline, pressure actuated means connected .to said valve and normally acting to open saidivalve, cylinders located adjacent said pressure actuated means and having outlet ports connected .to said pressure actuated means and provided with inlet ports, reservoirs connected to the inlet ports, pipes connecting the reservoirs to the pipeline, check valves in said pipes, pistons operating in said cylinders, pipes connecting the cylinders to the pipeline whereby pressure in the pipeline may become equal on each side. of the pistons, valves connected to the pistons, springs acting .on the pistons for normally positioning .said pistons to bring about closing of the outlet ports of the cylinders by said valves to normally .closethe pipeline pressure to the pressure actuating means and adapted to admit pressure from the reservoirs to said pressure actuatedmeans on the pressure in the pipeline decreasing .dueto leakage.

:MAVIN A. THOMASON. 

